1、Designation: D823 95 (Reapproved 2012)Standard Practices forProducing Films of Uniform Thickness of Paint, Varnish,and Related Products on Test Panels1This standard is issued under the fixed designation D823; the number immediately following the designation indicates the year oforiginal adoption or,
2、 in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1
3、 Five practices are given for preparing films of uniformthickness of coatings on test panels. These practices are:Practice AAutomatic Spray Machine ApplicationPractice BMotor-Driven Dip Coater ApplicationPractice CMotor-Driven Blade Film ApplicationPractice DHand-Held Spray Gun ApplicationPractice E
4、Hand-Held Blade Film Application1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user o
5、f this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelate
6、d Coating ProductsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base (Withdrawn 2006)3D1212 Test Methods for Measurement of Wet Film Thic
7、k-ness of Organic CoatingsD1400 Test Method for Nondestructive Measurement of DryFilm Thickness of Nonconductive Coatings Applied to aNonferrous Metal Base (Withdrawn 2006)3D3924 Specification for Environment for Conditioning andTesting Paint, Varnish, Lacquer, and Related MaterialsPRACTICE AAUTOMAT
8、IC SPRAY MACHINEAPPLICATION3. Summary of Practices3.1 A liquid material is applied to a test panel by means ofan automatic spray machine consisting of a mounted spray gunand a panel holder. This machine can (1) move the panelholder, with test panel, at a uniform speed through theatomized spray produ
9、ced by a fixed spray gun, or (2)itcanmove the gun, with atomized spray, at a uniform speed past thetest panel mounted on a fixed panel holder. A machineequipped with a programmable system can index the spray gunvertically for multiple passes and for multiple coats withselective time delay.3.2 The th
10、ickness of coating applied is controlled by thetraverse speed of the panel or gun, the fluid delivery rate of thegun, the viscosity of the material, and the amount of nonvola-tile matter in the material.4. Significance and Use4.1 These practices should be used for those coatings thatare designed for
11、 spray applications of objects in the factory orin the field. It is particularly important that it be used in theevaluation of metallic coatings for appearance properties, suchas gloss and color.4.2 Coatings applied by this test method may exhibit a slightorange-peel or spray wave.5. Apparatus5.1 Te
12、st Panels, of any smooth, planar material of a size thatcan be accommodated by the panel holder of the automaticspray machine.5.1.1 When steel panels are used, they should be prepared inaccordance with the appropriate method in Practice D609.1These practices are under the jurisdiction of ASTM Commit
13、tee D01 on Paintand Related Coatings, Materials, and Applications and are the direct responsibilityof Subcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Nov. 1, 2012. Published November 2012. Originallyapproved in 1945. Last previous edition approved in 2007 a
14、s D823 95 (2007).DOI: 10.1520/D0823-95R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved
15、version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Automatic Spray Machine, equipped with a panel holderand a mounting for a spray gun. The machine shall be designedto
16、move the panel holder at a uniform speed past the fixed gunmount, or designed to move the gun mount at a uniform speedpast the fixed panel holder. The panel holder or the gun mounttraverse speed shall be adjustable from 7.5 to 30 m (25 to 100ft)/min. Typical machines are shown in Fig. 1.NOTE 1Some a
17、utomatic spray machines provide additional featuresthat can improve the uniformity of film preparation. Some examples are:a z-bar panel holder; indexing of the panel holder at right angles to the gunto provide uniform lapping; and automatic control of number of passes,time between passes, and lappin
18、g distance.5.3 Spray Gun, any that will provide a uniform fan-typespray pattern at least 150 mm (6 in.) in width is satisfactory.The gun may be triggered manually or automatically.5.4 Pressure Gage, covering the range of 0 to 690 kPa (0 to100 psi).5.5 Air Pressure Regulator.5.6 Air Supply, oil-free,
19、 under pressure.6. Preparation of Apparatus6.1 Mount the spray gun on the automatic spray machine.Connect the air line hose from the regulator to the air pressuregage which in turn is connected to the air inlet of the spray gun.6.2 Set the gun so that its tip is at the desired distance fromthe test
20、panel surface, usually in the range from 200 to 300 mm(8 to 12 in.).6.3 With the gun trigger fully open, adjust the air regulatorto provide the desired reading on the air pressure gage.NOTE 2A suitable air pressure is usually from 275 to 520 kPa (40 to75 psi).6.4 Set the automatic spray machine cont
21、rols to provide thedesired traverse speed of the panel holder or the gun mount,whichever is pertinent to the type of machine being used.NOTE 3Suitable traverse speeds for automative coatings usually rangefrom 17.5 to 22.5 m/min (700 to 900 in./min ).7. Procedure7.1 Strain the material to be sprayed
22、into the container to beused with the spray gun. Reduce the material to a viscositysuitable for spraying.7.2 Connect the container to the gun and test the spray gunoperation while stationary, for correct spray pattern and uni-formity by allowing a momentary spray to be deposited on apiece of paper p
23、laced in the panel position. Adjust the airpressure material flow, and spray fan width controls until thedesired pattern and uniformity are obtained. Further refine-ments may be made in the spray pattern by modifying the airpressure, the type of thinning agent, and the consistency of thematerial.NOT
24、E 4The width of the spray pattern should be considerably widerthan the width of the test panel to assure spray uniformity on the testpanel.7.3 Place a test panel on the panel holder and start themachine. Operate the spray gun so that it will begin spraying afew seconds before the test panel enters t
25、he spray pattern andcontinue spraying a few seconds after the test panel leaves thespray pattern.7.4 Remove the coated panel and bake, force-dry, or air-dryit, in accordance with its type, in a vertical position in adust-free atmosphere, as described in Specification D3924.7.5 Determine the thicknes
26、s of the coating in accordancewith Test Methods D1005, D1186, D1212,orD1400, which-ever is appropriate.8. Report8.1 Report the following information:8.1.1 Type of coating material,8.1.2 Viscosity and percent of nonvolatile coating material,8.1.3 Distance of test panel from gun tip,8.1.4 Air pressure
27、,8.1.5 Number of spray passes,8.1.6 Traverse speed,8.1.7 Temperature and relative humidity at time ofapplication, and8.1.8 Film thickness values obtained for applied coating.PRACTICE BMOTOR-DRIVEN DIP COATERAPPLICATION9. Summary of Practice9.1 A motor-driven device is employed to withdraw the testpa
28、nel from a container of the coating material at a desireduniform rate.9.2 The thickness of coating applied is controlled by thespeed of panel withdrawal, the viscosity of the material, andthe percent of solids in the material.10. Significance and Use10.1 This test method is limited to those material
29、s that flowout to smooth films when test panels are dipped into thematerial and withdrawn.11. Apparatus11.1 Dip Coater, consisting of a mechanism that will with-draw a panel from a container of the coating material at apredetermined rate. Suitable apparatus, is shown in Fig. 2(a)and 2(b):11.1.1 The
30、apparatus shown in Fig. 2(a) uses a cord woundaround a step-cone pulley on the shaft of a motor to providepanel withdrawal rate of 50, 75, and 100-mm (2, 3, and 4-in.)/min. Prior to withdrawal, the panel, attached to the cord, islowered by hand into the container holding the material.11.1.2 The appa
31、ratus shown in Fig. 2(b) uses a cord drivenby a variable-speed device that can provide panel immersionand withdrawal rates that are continuously variable from 65 to510 mm (2.5 to 20 in.)/min.NOTE 5Rectangular containers (F-style can with lid cut off) are usefulbecause the smaller exposed surfaces of
32、 the liquid coating reduces volatileloss.11.2 Test Panels, of any clean, smooth, rigid substrate of asize that can be accommodated by the dip coater and thecontainer.D823 95 (2012)2(a) Fixed Gun, Traveling Panel Machine (b) Fixed Panel, Traveling Gun Machine(c) Fixed Panel Programmable Indexing Trav
33、eling Gun MachineFIG. 1 Automatic Spray Machines, Practice AD823 95 (2012)311.2.1 When steel panels are used they shall be prepared inaccordance with the appropriate method in Practice D609.NOTE 6The test panels should not exceed 300 mm (12 in.) in length,but the width may be varied up to 300 mm (12
34、 in.) if a suitablecounterweight is used and a dip tank of adequate size is provided. Use ofa multiple hook will permit dipping several panels at one time.12. Procedure12.1 Adjust the coating material to the proper percentage ofsolids and viscosity. Measure the temperature of the material inthe cont
35、ainer at the time of application.NOTE 7The operating conditions (viscosity, percent of nonvolatilematter, and rate of withdrawal) are specific for a given coating materialand film thickness and need to be determined by trial. Subsequentreproduction of the same operating conditions should give the sa
36、me filmthickness. Data are available4on a variety of materials and film thicknessto indicate the range required. The viscosity range for normal filmthickness of 13 to 50 mm (0.5 to 2.0 mil ) has been shown to be 1 to 2.5P.12.2 Place the prepared test panel on the hook attached tothe cord and lower i
37、t into the container holding the coatingmaterial. Wind the cord once completely around the pulley ofthe correct size to give the desired rate of withdrawal.12.2.1 For the stepped-cone pulley apparatus, wind the cordonce completely around the pulley of the correct size to givethe desired weight of wi
38、thdrawal.12.2.2 For the continuously variable speed apparatus set thedesired panel immersion and withdrawal rates on the controlpanel.12.3 Start the motor and withdraw the panel at the desiredrate, with a smooth movement entirely free of vibration. Bake,force-dry, or air-dry the coated panel, in acc
39、ordance with itstype, in a vertical position in a dust-free atmosphere inaccordance with Specification D3924.12.4 Determine the thickness of the coating in accordancewith Test Methods D1005, D1186,orD1400, whichever isappropriate.12.5 If the coating thickness is too low, coat another panelusing a sl
40、ower rate of panel withdrawal. If the coatingthickness is too high, coat another panel using a faster rate ofpanel withdraw.4Information covering viscosity, percent of solids, rates of withdrawal and filmthickness for a variety of finishing materials is given in the paper by Payne, H. F.,“The Dip Co
41、ater, An Instrument For Making Uniform Films by the Dip Method,”Industrial and Engineering Chemistry, Analytical Edition, Vol 15, 1943, p. 48.(a) Dip-Coater With Motor-Driven Step-Cone Pulley (b) Dip-Coater With Continuously Variable Speed DriveFIG. 2 Dip-Coater, Practice BD823 95 (2012)412.6 Contin
42、ue in this manner until a test panel having thedesired film thickness is produced. Measure thickness on atleast three different areas of the test panel to determine coatinguniformity.NOTE 8With the dip coater, non-uniform thickness on a panel isfrequently obtained. Hence, if the film thickness is gr
43、eater at the bottomthan the top, the viscosity should be increased or the panel withdrawalspeed should be reduced, or both.13. Report13.1 Report the following information:13.1.1 Type of coating material,13.1.2 Viscosity, temperature, and percent nonvolatile ofcoating material,13.1.3 Rate of withdraw
44、al,13.1.4 Air temperature and relative humidity at time ofapplication, and13.1.5 Mean and range of dry film thickness values ob-tained.PRACTICE CMOTOR-DRIVEN BLADE FILMAPPLICATION14. Summary of Practice14.1 A uniform film is produced by an applicator blade thatis pushed across the test panel at a un
45、iform speed by amotor-driven device.14.2 The thickness of coating applied is controlled by theclearance of the applicator blade and the viscosity and percent-age of solids of the material.15. Significance and Use15.1 This test method is applicable to substrates consistingof smooth rigid materials, s
46、uch as metal or glass, and ofnon-rigid materials, such as paper charts. It is more reliable forproducing uniform films than is the use of hand-held draw-down applicators.16. Apparatus16.1 Motor-Driven Blade Film Applicator,5consisting of abase plate, a bar for holding an applicator blade, and a driv
47、ingmechanism. The base plate shall hold paper charts flat bymeans of a vacuum. The blade holder shall be designed toaccommodate common types of applicator blades and to acceptweights for loading the applicator blade. A mechanism shall beprovided to stop the blade movement automatically at the endof
48、the draw-down. A suitable apparatus is shown in Fig. 3.16.2 Vacuum Source, a vacuum pump or a water aspirator.16.3 Applicator Blade, any common type, either with ad-justable or fixed clearances.16.4 Test Panels, any clean, smooth, rigid substrate or maybe paper charts or similar materials.NOTE 9Rigi
49、d panels shall be cleaned in an approved manner. Steelpanels shall be prepared in accordance with the appropriate method inPractice D609.17. Procedure17.1 Clean the base plate and place the test panel on it.17.2 If a vacuum is needed to hold the test panel flat,connect the vacuum source to the base plate and turn it on.NOTE 10When films are being applied to paper charts or tin foil, asheet of paper should first be placed on the vacuum plate to preventformation of dimples at the plate perforations.5Suitable apparatus may be obtained from several suppliers of pai
